Electrical testing apparatus



(No Model.) 2 Sheets-Sheet l. G. E. RUDD.

ELECTRICAL TESTING APPARATUS. No. 504,751. Patented Sept. 12E 1893 (No Model.) v 2 Sheets-Sheet 2.

G. H. RUDD.

ELECTRICAL TESTING APEAEATUS.

No. 504,751. Patented Sept. 12, 1893.

Il I u UNITED STATES PATENT OFFICE.,

CHARLES II. RUDD, OF EVANSTON, ASSIGNOR TO THE 'WESTERN ELECTRIC COMPANY, OE CHICAGO, ILLINOIS.

ELECTRICAL TESTING APPRATUS.

SPECIFICATION forming part of Letters Patent No. 504,751, dated September 12, 1893.

Application filed January 14, 1888. Serial No. 260,944. (No model.)

To @ZZ whom t may concern:

Be it known that l, CHARLES H. RUDD, a citizen of the United States, residing at Evanston, in the county of Cook and State of lilinois, have invented certain new and useful Improvement in Electric-Light-lestin g Apparatus, (Case No. 1,) of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawro ings, formingapart of this specification.

My invention relates to apparatus for test.- ing to determine whether there is any ground or leak upon an electric arc light circuit.

Myinvention consists in a telephone on one z5 side of which is a condenser and on the other side a connecting device for closing the telephone circuit to any portion ot' the electric light circuit. This connecting device may be a rod or pole to be held in the hand and 2o reached up to the lamp hooks, or a dial device may be used provided with normally open branch connections to different sides of the dynamo machine, so branched that the telephone may be readily connected to either branch at will. The inspector listening at the telephone and noting the edect in the telephone, is able to determine whether or not there is any leak or ground throughout the circuit. The tests are made while the lamps 3o are burning and the location of the leak or ground is determined by listeningr at the telephone and noting the loudness of the sound due to the currents drawn off from the circuit at points of different potential. It is well 3 5 known that if a ground is established between two lamps, little or no current would be sent through a branch connected to ground between the same lamps, but if a connection were made to ground at some other point in 4o the circuit so that there should be intervening lamps between the two ground connections, a strong current would be established through the new ground connection. A condenser included in a ground branch, permits the vibratcry currents or waves to pass through the telephone so as to cause sounds in the telephone practically the same as if the circuit were direct to ground. This function of a condenser in a telephone circuit is 5c well known. The experienced inspector will Soon learn by the difference in the loudncss of sound in the telephone as he makes connection at different points of an electriclight circuit, the direction or location of the leak or ground, if any.

My invention involves not only the apparatus, but the method of using the same to determine the location of accidental leaks or grounds upon electric light circuits.

The claims upon the apparatus I have in- 6o seried in a division of this case, Serial No. 289,088, filed October 25, 1888, for testing apparatus for electric light circuits.

My invention is illustrated in the accompanying drawings, in which- Figure l shows an electric lamp, electric lamp circuit and my testing apparatus applied to one side of the lamp as in the act of making a test. Fig. 2 is a diagram illustrative of my dial device provided with termi- 7c nals connected with different sides of dynamo electric machines at an electric light station. Fig. 3 is a sectional View of the dial upon line :c a: of Fig. 2.

As shown in Fig. lit will be seen that the 7; telephone is included in a circuit branched through a condenser a to the ground b. The pole is held in the hand and attached to the hook of the lamp. I have made the ground connection b in the form of a hook, so that it may 8o be conveniently thrown over a gas pipe for making the ground connection readily. The circuit is connected through the pole to the point c so that when the point c is touched to the hook or other portion of the lamp circuit, the circuit will be closed through the pole to the telephone and condenser to ground. Any convenient form of apparatus may be used.

As shown in Figs. 2 and 3, the dial cl is pro- 9c vided with terminals e f g h, whichterminals are connected with different sides of the dynamo machines l and 2, as shown. The 1ever t corresponds, in function, to thepole. It may be moved over anyone of the terminals ef g 71, and closed thereon as desired. This dial is designed especially to be placed at an electric light station. Each separate lamp circuit is provided with two terminals upon the dial, one terminal leading to one side of roo the dynamo electric machine or machines, and the other to the other side of the dynamo electric machine or machines. If the lever t' be closed upon point e, no sound Will be heard in the telephone unless there be a leak or ground at some point of the circuit, and if the leak or ground should be between the dynamo and the rst lamp, there would still be no current sent through the telephone. or other current indicating apparatus, included in the circuit with the condenser. I therefore ind it necessary to provide for testing on opposite sides of the machine, and therefore after a test has been made upon the point e, I move the lever t over to point f connected with the opposite side of the machine. In this manner a leak'or ground will be surely detected, if any exist at any point throughout the circuit. The engineer or inspectorin order to test a circuit, therefore, will preferably test first at the station connecting With opposite sides of the generator. If the telephone or other current indicating apparatus does not show appreciable current when connection is made With either side, it Will be considered that the circuit is perfect. It, however, current should be indicated when connection is made with either side or with both sides, the inspector Will go out along the line with apparatus similar to the apparatus shown in Fig. 1, and will touch the point c of his testing apparatus to the lamps on diftererent sides at diierent points along the route until he arrives at a point Where no current is indicated When said point c touches a hook on one sideof a lamp. This Willindicate that the ground is upon that particular side of the lamp which he is testing and between that lamp and the next. Thus the ground or leak may be readily traced upon any electric light circuit.

I do not limit myself to the construction shown, since the construction may be varied in various ways Without departing from my invention.

Having thus described my invention, I claim as new and desire to secure by Letters Patent-- l. The method of testing an electric lamp circuit, which consists in successively connecting or tapping a telephone with said circuit at different points while the lamps are burning, and listening at the telephone and comparing the sounds produced in the telephone at the different points with respect to loudness, substantially as described.

2. The method of testing electric light circuits While the lamps are burning, which consists in successively closing different points of the circuit to ground through a telephone and condenser, and listening at the telephone as the connections are made and comparing the loudness of sounds in the telephone to determine the relative potentials of the current at the dilerent points.

3. The method of detecting grounds upon an electric circuit supplied with a non-uniform current, which consists in applying successively at various points along the line, an indicating device adapted to be actuated by a non-uniform current to give an indication, said indication adapted to vary as the strength of the current varies, and noting the character of the indication,substantially as described.

In Witness whereof I hereunto subscribe my name this llth day of January,A. D. 1888.

CHARLES H. RUDD.

Witnesses:

GEORGE P. BARTON, C. C. WooDWoR'rH. 

